As you can see here, looking casually smart doesn't take that much effort. Consider wearing a blue suit and a crew-neck t-shirt and be sure you'll look amazing. You can take a more relaxed approach with shoes and introduce dark brown athletic shoes to the mix. There's no better way to spice up a gloomy fall day than a cool ensemble like this one. Wondering how to master casual outfits in your twenties? This pairing is the perfect answer.